Problem: Constraints

* H is an integer between 2 and 50 (inclusive).
* W is an integer between 2 and 50 (inclusive).
* s_{i, j} is `.` or `#` (1 \leq i \leq H, 1 \leq j \leq W).
* s_{1, 1} and s_{H, W} are `.`.

Input

Input is given from Standard Input in the following format:


H W
s_{1, 1}s_{1, 2}s_{1, 3} ... s_{1, W}
s_{2, 1}s_{2, 2}s_{2, 3} ... s_{2, W}
:   :
s_{H, 1}s_{H, 2}s_{H, 3} ... s_{H, W}


Output

Print the maximum possible score that Snuke can achieve, or print -1 if the game cannot be completed.

Examples

Input

3 3
..#
#..
...


Output

2


Input

3 3
..#
..
...


Output

2


Input

10 37
.....................................
...#...####...####..###...###...###..
..#.#..#...#.##....#...#.#...#.#...#.
..#.#..#...#.#.....#...#.#...#.#...#.
.#...#.#..##.#.....#...#.#.###.#.###.
.#####.####..#.....#...#..##....##...
.#...#.#...#.#.....#...#.#...#.#...#.
.#...#.#...#.##....#...#.#...#.#...#.
.#...#.####...####..###...###...###..
.....................................


Output

209

Solution (in PYTHON3):

Solution:
from collections import deque
h,w=map(int,input().split())
grid=[input() for _ in range(h)]
vis=[[0]*w for _ in range(h)]
vis[0][0]=1
que=deque([(0,0)])
while que:
	p,q=que.popleft()
	for x,y in ((-1,0),(0,-1),(1,0),(0,1)):
		if 0<=p+x<w and 0<=q+y<h and vis[q+y][p+x]<1 and grid[q+y][p+x]==".":
			vis[q+y][p+x]=vis[q][p]+1
			que.append((p+x,q+y))
if not vis[h-1][w-1]:
	print(-1)
else:
	print(h*w-sum(c.count("#")for c in grid)-vis[h-1][w-1])